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Update on the STATEMAP mapping program in Arizona

Article Author(s):

Jon Spencer

Figure 1. Geologic map of Arizona showing areas that have been mapped during the past 20 years as part of the STATEMAP program (dark blue), maps that were completed for STATEMAP 2012 but that are in drafting (light blue), maps that are in progress (dark green, and for the geodatabase of Quaternary geology and aggregate resources, lavender), and maps that are planned for 2014.

The STATEMAP program is a component of the National Geologic Mapping Act of 1992. STATEMAP is a matching fund program whereby State general funds are matched one-to-one by federal funds to support geologic mapping by the states. The Arizona Geological Survey (AZGS) has participated in the STATEMAP program since its inception, and has produced 1:24,000-scale geologic maps of a large fraction of the State with funding from this program (Figure 1). Seven new geologic maps, currently in drafting but otherwise complete, represent the products of the 2011-2012 field season (STATEMAP 2012; Figure 1). Five more geologic maps are currently in progress for STATEMAP 2013, as well as a map database (a “geodatabase”) of the greater Phoenix metropolitan area and surrounding ranges that will show areas of aggregate resources (Figure 1).

For the September 2013 to September 2014 STATEMAP contract period, Arizona will receive $151,162 from the USGS for new geologic mapping, to be matched by $151,261 in State funds. Five 7.5’ Quadrangles will be mapped with these funds during the 2013-2014 mapping season (Figure 1). Two of these Quadrangles are located in the Kingman area in Mohave County, and include the Kingman 7.5’ Quadrangle. This area was selected partly because U.S. Route 93 is under consideration for re-routing where it meets I-40. New detailed geologic maps would be useful for the route-selection process. The other three Quadrangles are located along the Colorado River in Mohave and La Paz Counties. This area was selected for mapping because of interest in aggregate deposits associated with the Colorado River, and because population growth rates and environmental geology concerns are high in the Colorado River Valley.

Aggregate-resource maps. In 2011, a new Arizona law was enacted requiring County Planning and Zoning Commissions to consider maintenance of access to aggregate resources in comprehensive development plans. Arizona Revised Statute 11-804 states that such commissions are required to include, in their land-use planning, “currently identified sources of aggregates from maps that are available from state agencies, policies to preserve currently identified aggregates sufficient for future development and policies to avoid incompatible land uses…” Although not explicitly stated in the new law, it is generally understood that the AZGS has the expertise to provide maps needed for aggregate-resource evaluation, and that the AZGS is the primary source for such information.

In 2012, the Arizona Geologic Mapping Advisory Committee, in response to this new law, voted overwhelmingly to recommend highest priority to new mapping in the Tucson metropolitan area (as it has the previous year for new mapping in the Phoenix area – see Figure 1). Specifically, they requested new mapping of sand and gravel deposits that are common along major washes. This mapping was intended to assist local planning and zoning commissions in complying with ARS 11-804.

Although the Tucson-area aggregate mapping was highly recommended by the Geologic Mapping Advisory Committee, the STATEMAP review committee determined that proposed map and database products would not be new geologic maps, but rather “derivative” maps created significantly from previously created maps. Although we at the AZGS disagree with this assessment, funding was reduced, the Tucson-area aggregate mapping component was deleted from the revised proposal, and we do not expect to request STATEMAP funds in the future specifically for aggregate mapping unless that mapping is done at 1:24,000 scale for previously unmapped 7.5’ Quadrangles.